Dynamic Planning for Obstacle Avoidance of Crawler Based on Gaussian Model

In order to solve the problems of obstacle avoidance planning and trajectory optimization of unmanned platform in hilly orchards, this paper proposes a dynamic planning algorithm based on Gaussian probability model to predict dynamic obstacle behavior. The technical route and method of theoretical derivation-algorithm design-simulation analysis-real vehicle testing are both adopted. Firstly, the global reference path of orchard is optimized based on the quadratic programming. Secondly, the intentions of surrounding pedestrians and other dynamic obstacles are estimated based on the Gaussian probability model. Subsequently, a dynamic grid map is created based on the Frenet coordinate system. Then, the obstacles avoidance paths are dynamically planned to obtain discrete optimal paths. Finally, the quintic polynomial curve is utilized to connect the sampling points to generate the path with continuous curvature. The analysis by ROS/Rviz simulation indicates that the planning time decreases by 57.97%, the number of sampled nodes decreases by 79.57%, and the curvature is smoother and continuous compared with the RRT algorithm. A field test is conducted on a hilly orchard road. With the Gaussian model, the algorithm can effectively predict the behavioral state of dynamic obstacles. The platform can autonomously plan a continuous, smooth and safe driving route in a shorter period of time, effectively avoiding obstacles and reducing the impact of steering-in-place on operating efficiency. Through the research, a dynamic obstacle behavior prediction and obstacle avoidance algorithm is proposed for the crawler chassis in hilly orchards based on the Gaussian probability model and dynamic programming, and the obstacle avoidance curve obtained by the algorithm satisfies the kinematic constraints of the crawler chassis, and has good safety, better real-time and enforceability. Additionally, a comprehensive set of software and hardware solutions for spontaneous static obstacle avoidance planning in hilly orchards is presented

Effect of Saturated Zone on Nitrogen Removal Processes in Stormwater Bioretention Systems

The introduction of a saturated zone (SZ) has been recommended to address the issue of nitrogen removal fluctuation in the bioretention system, which is one of the most versatile low-impact development facilities for urban stormwater management. Nine experimental columns were used to characterize the nitrogen concentration variations over the outflow during wetting periods and in SZ during the antecedent drying periods (ADPs), as well as compare removal efficiencies of various nitrogen species in systems with different SZ depths under alternate drying and wetting conditions. Results indicated that NO3−-N concentrations in the outflow showed quasi-logistic curve-shaped variations over time: being low (<0.5 mg/L) in the early process, sharply increasing thereafter, and finally flattening around 3.0 mg/L with NO3− leaching; NH4+-N and organic nitrogen (ON) concentrations were consistently low around 0.5 mg/L and 1.8 mg/L, respectively during the wetting periods. NH4+ removal efficiency in bioretention systems was consistently high around 80%, not varying with the increasing SZ depth; ON removal efficiency had a slight rise from 57% to 84% and NO3− removal efficiency was significantly enhanced from −23% to 62% with the SZ depth increasing from 0 to 600 mm. Deeper SZ could store more runoff and promote more denitrification of NO3− and mineralization of ON during the ADPs, providing more “old” water with low NO3− and ON concentrations for water exchange with “new” inflow of higher NO3− and ON concentrations during the wetting periods. The total nitrogen (TN) removal, a combined result of the instantaneous removal through adsorption and retention in the upper soil layer during the wetting periods and the gradual removal via denitrification and mineralization in SZ during the ADPs, was also improved by increasing the SZ depth; TN removal efficiency was elevated from 35% to 73% when the SZ depth increased from zero to 600 mm

Temperature-Responsive Switch Constructed from an Anthracene-Functionalized Pillar[5]arene-Based Host–Guest System

A monofunctionalized anthracene pillar[5]­arene (MAP5) was designed and synthesized by a click reaction. MAP5 was bound to an ionic liquid through host–guest interactions to modify a gold interface. The bonding and release of MAP5 was readily and reversibly controlled by temperature regulation. The developed temperature-responsive switch at an interface can be used in memory storage, drug delivery, and sensing

Full-function Pavlov associative learning photonic neural networks based on SOA and DFB-SA

Pavlovian associative learning, a form of classical conditioning, has significantly impacted the development of psychology and neuroscience. However, the realization of a prototypical photonic neural network (PNN) for full-function Pavlov associative learning, encompassing both photonic synapses and photonic neurons, has not been achieved to date. In this study, we propose and experimentally demonstrate the first InP-based full-function Pavlov associative learning PNN. The PNN utilizes semiconductor optical amplifiers (SOAs) as photonic synapses and the distributed feedback laser with a saturable absorber (DFB-SA) as the photonic spiking neuron. The connection weights between neurons in the PNN can be dynamically changed based on the fast, time-varying weighting properties of the SOA. The optical output of the SOA can be directly coupled into the DFB-SA laser for nonlinear computation without additional photoelectric conversion. The results indicate that the PNN can successfully perform brain-like computing functions such as associative learning, forgetting, and pattern recall. Furthermore, we analyze the performance of PNN in terms of speed, energy consumption, bandwidth, and cascadability. A computational model of the PNN is derived based on the distributed time-domain coupled traveling wave equations. The numerical results agree well with the experimental findings. The proposed full-function Pavlovian associative learning PNN is expected to play an important role in the development of the field of photonic brain-like neuromorphic computing

A semi-scaled experiment for metals separating and recovering from waste printed circuit boards by slurry electrolysis

Waste printed circuit boards (WPCBs) are considered as the most complicated and valuable component among e-waste. Slurry electrolysis can separate and recover metals from the extremely complex WPCBs. To promote its industrial application, a 5000 mL scale experiment was conducted to confirm industrial feasibility. Those results showed that copper and total metal recovery rates were 94.5 % and 75.2 % under the optimized conditions (30 g/L WPCBs, 10 g/L CuSO4 center dot H2O, 30 g/L NaCl, 190 g/L H2SO4, 30 g/L H2O2, 298 K temperature, 250 r/min stirring speed, 300 A/m(2) and 8 h). The copper purity was 92.9 %, and SEM-EDS analyses indicated the main dendritic metals recovered were copper and lead. USEtox toxicity potential evaluation results demonstrated human toxicity and ecotoxicity of WPCBs sharply decreased after treatment. A cost analysis of this process indicated that the $1.0 cost was partially offset by the$ 1.9 return from 1 kg WPCBs. Thus, slurry electrolysis has a promising industrial future for e-waste recycling/utilization. (C) 2020 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.</p

The Associations between Meeting 24-Hour Movement Guidelines (24-HMG) and Mental Health in Adolescents—Cross Sectional Evidence from China

(1) Background: This study determined the prevalence of adolescents that meet 24-HMGs alone and in combination, and their association with the risk of developing adolescent anxiety and depression. (2) Methods: Participants were drawn from 9420 K8 grade adolescents (age 14.53 ± 0.69 years; 54.78% boys) from the China Education Tracking Survey (CEPS) 2014–2015 tracking data. Data on depression and anxiety were collected from the results of the questionnaire in the CEPS for the adolescent mental health test. Compliance with the 24-HMG was defined as: physical activity time (PA) ≥ 60 min/day was defined as meeting the PA. Screen time (ST) ≤ 120 min/day was defined as meeting the ST. Adolescents aged 13 years achieved 9–11 h of sleep per night and adolescents aged 14–17 years achieved 8–10 h of sleep per night, defined as meeting sleep. Logistic regression models were used to examine the association between meeting and not meeting the recommendations and the risk of depression and anxiety in adolescents. (3) Results: Of the sample studied, 0.71% of adolescents met all three recommendations, 13.54% met two recommendations and 57.05% met one recommendation. Meeting sleep, meeting PA+ sleep, meeting ST + sleep, and meeting PA + ST + sleep were associated with a significantly lower risk of anxiety and depression in adolescents. Logistic regression results showed that differences in the effects of gender on the odds ratio (ORs) for depression and anxiety in adolescents were not significant. (4) Conclusions: This study determined the risk of developing depression and anxiety in adolescents who met the recommendations for 24-HMG alone and in combination. Overall, meeting more of the recommendations in the 24-HMGs was associated with lower anxiety and depression risk outcomes in adolescents. For boys, reducing the risk of depression and anxiety can be prioritised by meeting PA + ST + sleep, meeting ST + sleep and meeting sleep in the 24-HMGs. For girls, reducing the risk of depression and anxiety may be preferred by meeting PA + ST + sleep or meeting PA+ sleep and meeting sleep in 24-HMGs. However, only a small proportion of adolescents met all recommendations, highlighting the need to promote and support adherence to these behaviours

Recovery of high purity copper from waste printed circuit boards of mobile phones by slurry electrolysis with ammonia-ammonium system

Waste printed circuit boards (WPCBs) are identified to be the most complex recycling materials among waste electrical and electronic equipment (WEEE). Slurry electrolysis with acidic system can directly separate and recover copper from WPCBs while current efficiency and purity were generally reduced due to deposition of impurity metals and the hydrogen evolution during recovery process. In ammonia-based system, copper can be selectively extracted and copper (II) ammine complexes generally react with metallic copper to form copper (I) ammine complexes, promoting current efficiency and purity. Therefore, an efficient ammonia-ammonium carbonate slurry electrolysis system is proposed for high purity copper recycling from waste printed circuit boards of mobile phones (WPCB-MPs). The factors affecting copper current efficiency and recovery rate are systematically discussed. These results indicate that appropriate increasing NH3 center dot H2O, (NH4)2CO3, Cu2+, NaCl concentration, solid-to-liquid ratio, current density and reaction time could effectively increase copper recovery rate and current efficiency. The current efficiency and recovery rate of copper are 95.2 and 90.4%, respectively under the optimum test conditions of 20 g/L Cu2+, 0.25 mol/L (NH4)2CO3, 4 mol/L NH3 center dot H2O, 30 g/L solid-to-liquid ratio, 1 mol/L NaCl, 20 mA/cm2, 3 h. Moreover, copper could be recovered at the cathode with a purity of 99.97%. Compared with acidic system, this study provides an efficient approach to recover high purity copper from WPCB-MPs, showing a prospective future for WEEE resource recycling

Microsphere-Based Microsensor for Miniature Motors’ Vibration Measurement

We present a microsphere-based microsensor that can measure the vibrations of the miniature motor shaft (MMS) in a small space. The microsensor is composed of a stretched fiber and a microsphere with a diameter of 5 μm. When a light source is incident on the microsphere surface, the microsphere induces the phenomenon of photonic nanojet (PNJ), which causes light to pass through the front. The PNJ’s full width at half maximum is narrow, surpassing the diffraction limit, enables precise focusing on the MMS surface, and enhances the scattered or reflected light emitted from the MMS surface. With two of the proposed microsensors, the axial and radial vibration of the MMS are measured simultaneously. The performance of the microsensor has been calibrated with a standard vibration source, demonstrating measurement errors of less than 1.5%. The microsensor is expected to be used in a confined space for the vibration measurement of miniature motors in industry

Pesticide Macroscopic Recognition by a Naphthol-Appended Calix[4]arene

A new naphthol-appended calix[4]­arene (NOC4) has been synthesized and characterized. NOC4 is clicked onto a microstructured Au surface and exhibits selective macroscopic recognition of metolcarb (MC) via contact angle measurements. The proposed wettability sensing device displays remarkable specificity and is fast and easy to use, which should be suitable for the rapid detection of MC in environmental monitoring